Here's the pouch/bag thing that came with my Omnifuel II.
A general view showing the size...
The multi-tool and grease are in the top of the pocket, which is quite deep and covers most of the width. Its bottom is about half an inch below the top of the burner (might be able to see the seam). It's tall enough to just fit the windshield thing in its folded state. It's also wide enough to take the pump.
The closure is just a metal hook at one top corner, and a webbing loop at the other...
When hooked in, it's like a dry bag closure...
It could be rolled up a bit, but the fabric is pretty stiff, so maybe only one or two folds to still be able to hook the bits together.
Inside, there are no dividers, slots or the like - just one big rectangular bag (with no gusseting)...
The pocket is too slim to fit the burner or the bottle, so it would seem that one is expected to just put the two big bits into the bag and let them bash against each other. The bag also strikes me as not being especially protective of the burner parts, especially the hose where it's attached to the burner. It's also not especially conducive to being rolled up, especially if the windshield is in the pocket.
I much prefer something like this...
The box is one of those clip-lid types, and this one is 900ml from Morrisons. The fit is quite tight but everything does go in...
The only downside with this particular box is that the hose needs to be unscrewed from the burner to get everything to fit nicely. Not a big deal, but I might experiment a bit more to see if I can get it in without doing that (maybe ditch the red bottle cap). The baccy tin contains the multi-tool, grease and a lighter, and has some room left for the spare jets if needed. It's a tin for flake pipe tobacco and is much smaller than the usual 2oz tins that are common for survival kits and the like.
The windshield doesn't fit in this box, but slips easily enough into a pocket in the brew kit bag. Ordinarily, I wouldn't use it, and if I did want to, I may well try to come up with something different that rolls up rather than folds.